Bug#942131: gnome-session: Setting PATH with environment.d does not work (in GNOME Wayland session)

[Andreas Kloeckner]

Package: gnome-session
Version: 3.34.1-1
Severity: normal

Dear Maintainer,

I am having issues that seem quite related to
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=869144
and the discussion there, however the conclusions reached there
don't seem to apply for me.

My `~/.config/environment.d/90-my.conf`:
```
PATH=$HOME/bin:$PATH
MOZ_USE_XINPUT2=1
```
And `systemctl --user show-environment  | egrep 'PATH|MOZ'` gives me:
```
PATH=/usr/local/bin:/usr/bin:/bin:/usr/games
MOZ_USE_XINPUT2=1
```
i.e. the modification of `$MOZ_USE_XINPUT2` stuck, but *something* got
in the way of changing the `$PATH`. My shell is zsh, and I observed that

- Commenting out the 'run this with a login shell' chunk of
  /usr/bin/gnome-session [1] has no effect.

  [1] https://gitlab.gnome.org/GNOME/gnome-session/blob/60e619b8a2cacc7b844fe6f0e206c895de68f890/gnome-session/gnome-session.in#L3-14

- Adding things to my .profile (with the relevant chunk of
  /usr/bin/gnome-session in place) also has no effect.

The environment.d generators seem to be picking up on my conf file in an
appropriate manner:

$ export PATH=yoink
$ /usr/lib/systemd/user-environment-generators/30-systemd-environment-d-generator
PATH=/home/andreas/bin:yoink
MOZ_USE_XINPUT2=1
GTK_MODULES=gail:atk-bridge:gail:atk-bridge
QT_ACCESSIBILITY=1

I would be grateful for any advice in figuring out why my PATH changes
don't make it to my GNOME session.

Thanks!
Andreas

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'stable-updates'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 5.3.2 (SMP w/8 CPU cores)
Kernel taint flags: TAINT_WARN, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=de_DE:de (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gnome-session depends on:
ii  gnome-session-bin      3.34.1-1
ii  gnome-session-common   3.34.1-1
ii  gnome-settings-daemon  3.34.0-3
ii  gnome-shell            3.34.1-1

gnome-session recommends no packages.

Versions of packages gnome-session suggests:
ii  desktop-base   10.0.3
ii  gnome-keyring  3.34.0-1

-- no debconf information